In high voltage integrated circuit (referred hereafter as HVIC), a bootstrap diode is often used. Taking a half-bridge drive circuit as an example, referring to FIG. 1, the working process of the half-bridge is that: when a floating power supply terminal VS is applied with a low level voltage, a terminal VCC charges a bootstrap capacitor 2 through a bootstrap diode 1, and supplies power to a power supply terminal VB on a high voltage side. When the terminal VS is applied with high voltage, the voltage of the terminal VS exceeds the voltage of the terminal VCC with the help of the bootstrap capacitor 2, the bootstrap diode is in a reverse blocking state, the terminal VS supplies power to a circuit on the high voltage side through the bootstrap capacitor 2. In the above process, the bootstrap diode needs to withstand high voltage, the bootstrap diode needs to have characteristics of small leakage and fast recovery, the common Schottky diode has a characteristic of fast switching, which means it can recover quickly, but it cannot withstand high voltage, and it cannot be used as a bootstrap diode.
In the high voltage integrated circuit of a prior art, in order to achieve above functions of the bootstrap diode, an external discrete device is often used, the diode chip and the high voltage integrated circuit chip are packaged together, but the essence is the same, i.e. an external diode which can withstand high voltage and recover fast is used to achieve a voltage bootstrapping, and supply power to a circuit on the high voltage side, referring to FIG. 1, the complexity of a design of a peripheral circuit is increased, the difficulty of a circuit debugging is increased, the cost of the circuit is increased.